Thursday, December 21, 2006

What is the mind-brain question? This phrase is not official, it's just how I think of the question of whether the mind, or the personality, who someone is, is entirely a function of the physical brain, or partly a function of a non-physical soul. Is there a part of me that exists separately from my body, that can continue to exist after my body dies? Many people believe that there is a non-material component, commonly called a soul or spirit, that makes up the personality and can exist without a material body.

In considering this question, when I look at what the body of evidence tells me, I would tend to say that there is no aspect of the mind/personality that is not entirely a function of the brain. That is, when the brain dies, the mind dies with it. Not a comforting notion for many of us, perhaps. Yet this is what the evidence suggests to me. What do I mean by "evidence"? In defense of the existence of the soul, we have a great deal of anecdotal reporting, whether of the "near-death-experience" and other "out-of-body-travel" variety on the one hand or ghostly sightings on the other. Frankly, anecdotal evidence exists to buttress all manner of fantastical creatures, from Bigfoot to the Chupracabra. As evidence is does not stand up. On the other side, there is a great deal of scientific evidence, repeatable evidence. There is, for example, the evidence of the effects of damage to the brain, where every conceivable aspect of who a person is, is verifiably dependent on the proper functioning of the brain.

Consider the tragic case of Alzheimer's disease. I have been witness to two grandparents dying of this disease, but not before the disease, bit by bit, erased their essences, everything that made them who they were. (I recommend this interactive tour of the brain that demonstrates and explains the effects of Alzheimer's on the brain.) Consider also the bizarre cases of brain damage that result in a man being convinced that the woman who claims to be his mother (and really is his mother) is an impostor; another man comes to believe he is on the verge of understanding the meaing of everything, from a grain of sand to his car; and a woman who, when asked to draw a picture of a flower, draws beautifully only the right half, not even being aware that she has left out the other half. (I believe this was a PBS documentary; I wish I had a recording of it!)

All of these things tell me that the human personality is completely brain-dependent. I welcome thoughtful discussion on this subject, especially if you disagree with me.

You're asking two questions here. First, is personality as we know it entirely dependent on a functioning brain, and second, is there any part of a personality that can persist after the brain has died. I think it is pretty well accepted that a functioning brain is necessary for a personality to exist in the physical world. Of course, so are functioning lungs and blood cells and the sun and an oxygen rich environment, and that certainly doesn't mean that there is no aspect of personality that isn't defined by these things. If you take away the brain, there is no physical interface with a personality, but that's true of all the other things, too. That doesn't mean that short of any of things a nonphysical aspect of personality wouldn't go on, there would just be no way for it to go on in any way in a physical world. Thus, it's logical to conclude that there would be no physical evidence of it. If you shoot someone in the head and they die, you're not going to see any more physical represenation of their personality. The physical tools they would need for this are gone, but perhaps these physical tools aren't required for a personality to exist in a spiritual/non-physical world. I believe the basic concept is that in the spiritual world, all the experiences and perceptions and personality traits someone has go on without needing a brain or a face or a body maintained at 98.6 degrees to exist.

The resulting question with this line of thinking is then what type of people would we be in a spiritual world. What would our equivalent physical brain be like? Our personality obviously changes as our brain changes, so what personality would be the one that is maintained in a spiritual world? I would imagine that our personality would exist in a spiritual world as it would in a physical world if it had a fully functional brain. There's obviously no physical evidence to support this conclusion, but if you take the example of Jesus, it seems from the Bible that when he appeared to the disciples after dying, his personality was the same as it was when he had a fully functional body, not the one that might have existed as his brain was ultimately damaged as he died.

Anyway, the bottom line ot me seems to be that you're looking for the wrong thing if you're trying to find physical evidence of a spiritual aspect that is independent of the physical world. If you rely on physical evidence, you're obviously going to arrive at conclusions that are exclusively physical. It's like looking for something that is microscopic with tools incapable of perceiving things on this scale (e.g., our eyes). If you rely exclusive on macroscopic evidence, you're going to have an exclusive macroscopic conclusion. We've discovered so much that exists beyond ther perception of our eyes that it seems entirely possible to me that there's more that exists beyond the perception of anything we've come up with so far. My opinion would be that if you're going to believe in a spiritual world, it's not going to be because of physical evidence. I suppose the early Christians had physical evidence based on what Jesus and his disciples did, but people after this probably believed based on other things.

Thanks for your comment, anon. A very thoughtful answer that I agree with, in the sense that a search for material evidence of a soul will not be fruitful. The basis for the belief in an immaterial side of a human being's existence must lie elsewhere. Also, the question of the makeup of a personality that persists after death is a very intertesting one. Would the personality of an infant remain infantile if it died at that stage of its life? et cetera. Makes for an absorbing line of thought. Thanks again.